A simple and fast Double-Flow microfluidic device based liquid-phase microextraction (DF-µLPME) for the determination of parabens in water samples.

A fast double-flow microfluidic based liquid phase microextraction (DF-µLPME) combined with a HPLC-UV procedure using diode array detection has been developed for the determination of the four most widely used parabens: Ethyl 4-hydroxybenzoate (EtP), Propyl 4-hydroxybenzoate (PrP), Butyl 4-hydroxybenzoate (BuP) and IsoButyl 4-hydroxybenzoate (iBuP) in water samples. Parabens have successfully been determined in environmental (lake and river water) samples with excellent clean up, high extraction efficiency and good enrichment factor using double-flow conditions. The microfluidic device consists of two micro-channels, which contain the acceptor and sample solution separated by a flat membrane (support liquid membrane). The sample (0.32mM HCl) and acceptor phase (5.6mM NaOH) are delivered to the µLPME at 10µLmin and 1µLmin flow rate, respectively. The extraction efficiencies are over 84% for all compounds in water samples with enrichment factors within the range of 9-11 and recoveries over 80%. The procedure provides very low detection limits between 1.6 and 3.5µgL. The extraction time and the volume required for the extraction are 5min and 50µL, respectively; which are greatly lower compared to any previous extraction procedure for parabens analysis. In addition, this miniaturized DF- µLPME procedure significantly reduces costs compared to not only the existing methods for paraben detection, but also to the existing analytical techniques for sample preparation.